Mortise lock retract mechanism

ABSTRACT

A thin casing adapted to fit in a recess between opposite faces of a door has a front plate mounted flush with the door edge through which extends a reciprocating latch bolt for engagement within an opening of a strike plate mounted upon the adjacent door frame. The latch bolt is spring urged into a normally extended position and is retracted by rotation of either an inside or an outside knob. Rotation of the knobs in either a clockwise or counterclockwise direction is transferred rotating one or the other of a pair of hubs mounted within the casing. Roll backs on the hubs engage a lever, one end of which is coupled to the latch bolt and the other end of which is pivotally mounted on the wall of the case. In one form of the device a lock is provided for blocking rotation of the outside knob, while the inside knob is free to withdraw the latch bolt. Openings in the casing on opposite sides of the hubs accomodate threaded sleeves and screws for fastening the knobs in place.

United States Patent 91 Sanders Aug. 7, 1973 MORTISE LOCK RETRACT MECHANISM [75] Inventor: Vernard W. Sanders, Los Angeles,

Calif.

[73] Assignee: Norris Industries, Inc., Los Angeles,

Calif.

[22] Filed: Feb. 7, 1972 [21] Appl. No.: 223,866

[52] U.S. Cl 70/146, 292/165 292/350, 292/356 [51] Int. Cl..... E05c 1/16 [58] Field of Search 70/146; 292/165, 292/185, 222, 224, 232, 245

[56] References Cited UNITED STATES PATENTS 477,446 6/1892 Page 292/224 602,886 8/1898 Voight 292/165 956,262 4/1910 Augenbraun 70/418 3,672,714

6/1972 Schultz ..292/34 Primary Examiner-Albert G. Craig, Jr. Attorney-Vernon D. Beehler et a1.

[57] ABSTRACT A thin casing adapted to fit in a recess between opposite faces of a door has a front plate mounted flush with the door edge through which extends a reciprocating latch bolt for engagement within an opening of a strike plate mounted upon the adjacent door frame. The latch bolt is spring urged into a normally extended position and is retracted by rotation of either an inside or an outside knob. Rotation of the knobs in either a clockwise or counterclockwise direction is transferred rotating one or the other of a pair of hubs mounted within the casing. Roll backs on the hubs engage a lever, one end of which is coupled to the latch bolt and the other end of which is pivotally mounted on the wall of the case. In one form of the device a lock is provided for blocking rotation of the outside knob, while the inside knob is free to withdraw the latch bolt. Openings in the casing on opposite sides of the hubs accomodate threaded sleeves and screws for fastening the knobs in place.

18 Claims, l8 Drawing Figures PAIENIEU AUG 7 m5 SHEET 1 0F 6 PATENIED AUG 7 I975 H mm SHEET 2 BF 6 MORTISE LOCK RETRACT MECHANISM The present invention concerns the mechanism used to withdraw the latch bolt of a mortise type lock.

Although this particular type of lock has been well known for many years during which numerous improvements have been made and concepts have been developed, the present invention not only involves means for withdrawing the latch bolt by operation of a knob but also makes possible employment of fewer components that are easily manufactured by low-cost means and which at the same time provide improved strength, security, long life, and ease of operation.

It is therefore, among the objects of this invention to provide a new and improved latch bolt operating mechanism having extra strength, security, ease of operation and long life.

Another object of the invention is to create a new and improved latch bolt operating mechanism which employs a minimum of parts which are produceable by low-cost means.

A further object is to provide a new and improved mortise type latch bolt operating mechanism which is smooth in operation and has a balanced action whereby input rotation and actuating force are approximately equal in either a clockwise or counterclockwise direction.

Among other objects is to provide unobstructed spaces adjacent the hubs of mortise type latch bolt operating mechanisms which contains openings in the casing through which fastening means may pass for securely attaching the knobs to the door faces without interference with the mechanism.

A further object is to provide a new and improved means for protecting a mechanism of the type made reference to against excess input force or over-rotation by the inclusion of limit stops that may also be used to provide knob locking when required.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter set forth, pointed out in the appended claims, and illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a side perspective view of a section of a door, having a mortise type lock mounted therein,

FIG. 2 is a longitudinal sectional view of the mortise lock on the line 2 2 of FIG. 1.

FIG. 3 is a cross sectional view on the line 3 3 of FIG. 2.

FIG. 4 is a fragmentary cross sectional view on the line 4 4 of FIG. 2.

FIG. 5 is a fragmentary cross sectional view on the line 5 5 of FIG. 2 showing the pivot bearing for the retra'ct arm.

FIG. 6 is a cross sectional view on the line 6 6 of FIG. 2.

FIG. 7 is a fragmentary longitudinal sectional view showing the latch bolt and retraction mechanism in retracted position.

FIG. 8 is a fragmentary side elevation view of the rollback action.

FIG. 9 is an exploded perspective view of the rollback parts of the form of invention in FIG. 1.

FIG. 10 is a side perspective view of a second form of the mortise type lock mounted in a door.

FIG. 11 is an exploded perspective view of the rollback parts of the form of invention of FIG. 10.

FIG. 12 is a longitudinal sectional view of one form of the invention of FIG. 10, with the mechanism in locked position.

FIG. 13 is a fragmentary longitudinal sectional view of a portion of the mechanism visible in FIG. 12 but with parts in a different operative position.

FIG. 14 is a fragmentary longitudinal sectional view similar to FIG. 12 but with the mechanism in unlocked position.

FIG. 15 is a longitudinal sectional view of another form of the invention of FIG. 10, with the mechanism in unlocked position.

FIG. 16 is a fragmentary longitudinal sectional view similar to FIG. 15 but with the mechanism in locked position. 1

FIG. 17 is a cross sectional view on the line 17 17 of FIG. 15.

FIG. 18 is a fragmentary cross sectional view on the line 18 18 of FIG. 16.

In an embodiment of the invention chosen for the purpose of illustration there is shown in FIG. 1 a mortise type lock, indicated generally by the reference character 10, mounted within a door 11. The mortise type lock 10 has a face plate 12 mounted flush with the door edge 13 and containing an opening 14 through which extends a reciprocating latch bolt 15. The latch bolt 15 is spring urged in a normally extended position forcooperative engagement within an opening 16 of a strike plate 17 that is mounted upon the adjacent door frame 18 and serves to retain the door 11 in a latched condition when closed.

For unlatching and opening the door 11, conventional door knobs l9 and 21 are employed. Rotational movement of the knobs 19 or 21 in either a clockwise or counterclockwise direction is coupled by connecting means to a mechanism within the housing 20 for retracting the latch bolt 15 from the opening 16 of the strike plate 17.

The connecting means for attaching the knobs is best seen in FIG. 3 and shows the conventional arrangement of a knob 19, on one side of the door 11. The knob 19 has a shank portion 22, rotatable within a bearing 24, in a rose assembly 26. The other knob 21 has a like shank portion 23 also rotatable within a bearing 25 in a rose assembly 27. The rose assembly 27 contains a pair of internally threaded posts 28, 29. The other rose assembly 26 contains a pair of sleeves 30, 31 that closely telescope over the posts 28, 29 and through which attaching screws 32, 33 threadably engage the posts 28, 29 clamping the rose assemblies 26, 27 containing the knobs.l9, 21 to the door 11.

The lock housing 20 consists of a case 34 and cover 35. Aligned openings 36 and 37 in the case and similar aligned openings 38 and 39 in the cover accomodate respectively the posts 28 and 29 and the sleeves 30, 31. The spacing and location is such that the mechanism is not interferred with, the openings also providing coaxial alignment of the knobs19, 21 with a hub 40 on the side served by the knob 19 and a hub 41 served by the knob 21. The hubs 40, 41 rotate within respective hearing openings 42 in the cover 35 and 43 in the case 34. The bearing openings 42 and 43 are provided with thin wall flanged low friction inserts 42' and 43' respectively. The knob 19 contains an inwardly extending spindle 44 of non-circular shape that engages a correspondingly matching opening 46 in the hub 40. Similarly the knob 21 is provided with a spindle 45 also of non-circular shape and matching a corresponding opening 47 in the hub 41. The spindles 44 and 45 also fit non-rotatably in the shank portions 22 and 23 of the respective knobs 19, 21.

The knob 19 is retained axially within the bearing 24 by a shoulder 50, adjacent the shank portion 22, and a thrust washer 52 which is secured to the remote end of the shank portion 22, by such means as staking or spinning over the end of the shank portion-The knob 21 is similarly retained in its bearing 25 by a shoulder 51 and thrust washer 53.

The mechanism within the housing 20 is best viewed in FIG. 2 in conjunction with FIGS. 8 and 9 which illustrates the arrangement of parts in the simpler of the two versions in the normal position with the latch bolt extended. The hub 40 has a pair of equally spaced rollbacks 60 and 61 located rearward with respect to the center of rotation. Stop shoulders 64, 65 are provided on the forward portions opposite the rollbacks 60, 61. When the hub 40 is rotated, depending on the direction of rotation, one of the rollbacks 60, 61 acts upon one or the other of cam surfaces 68, 69 of a retract arm 70 causing it to pivot about the axis of bearing 71 in a rearward direction. Located at the upper end of the retract arm 70 is an arcuate contact surface 72 which moves in an arcuate path as the retract arm 70 is cammed in a rearward direction, whereby the contact surface 72 acts against a retract plate 73-resulting in retracting the latch bolt 15 from its normally extended position to a retracted position such that the outermost portion of the latch bolt 15 is approximately flush with the face plate 12. This position is illustrated in FIG. 7 of the drawings where the rollback 60 of the hub 40 has been rotated in a counterclockwise direction against the cam surface 68 of the retract arm 70. FIG. 8 shows the hub 40 rotated in the opposite or clockwise direction wherein the rollback 61 engages the cam surface 69.

Theretraet arm 70 is biased in a direction towards the hubs 40 and 41 by a torsion spring 74. The bias of the spring 74 rotates both hubs 40, 41 back to their normal position when the knobs 19 or 21 are released, whereby the cam surfaces 68, 69 acting against the rollbacks 60, 61, 62 and 63 result in a detent like situation.

The hub 41 is manipulated in a similar manner by rotation of the knob 21. On the hub 41 are rollbacks 62 and 63 for engagement with the respective cam surfaces 68 and 69 which act only when the knob 21 is rotated. Accordingly the latch bolt can be withdrawn by operation of either knob. The hub 41 is also provided with stop shoulders 66 and 67 on the forward portion opposite the rollbacks 62, 63.

To provide an equal amount of rotation and operating torque the cam surfaces 68, 69 of the retract arm 70 are set at different angles and lengths relative to the rollbacks 60, 62 and the rollbacks 61 and 63 and the distance from the axis of bearing 71.

The retract plate 73 previously identified is connected to the latch bolt 15 by a rod-like tail 75 details of which are best seen in FIGS. 2, 6 and 7. The tail is anchored to the latch bolt 15 at the forward end by having a close fit within a hole 76 at the rear of the latch bolt 15 where it is permanently retained by the pin 77 in the cross bore 78. The opposite end of the tail 75 is shouldered to receive the retract plate 73 which is permanently retained by the staking 79.

The latch bolt 15 is urged to extended position by the bias of a spring 80 against the rear surface of the latch bolt 15 and a guide member 81 which has a U shaped cutout for the purpose of maintaining axial alignment of the latch bolt 15, the tail 75 and the retract plate 73 when in reciprocating movement.

The amount of projection of the latch bolt 15 when extended is controlled by the retract plate 73 being in contact with the arcuate surface 72 of the retract arm 70. Rearward movement or retraction is controlled by the stop pin 82.

Once maximum retraction has been achieved, as seen in FIGS. 2 and 7, further stress on any component of the retraction mechanism by continued torque exerted by rotation of the knobs 19 or 21 is eliminated by the stop shoulders 64 or 65 of the hub 40 or by stop shoulders 66 or 67 of the hub 41. As shown in FIGS. 7 and 8, the stop shoulders 64 or 65 of the hub 40 are in stopped engagement with an adjacent end portion 83 of a stop 84 depending upon the direction of rotation. A like situation will occur when the hub 41 is rotated whereby stop shoulders 66 or 67 will contact the end portion 83 of the stop 84.

In the forms of the invention shown in FIGS. 10 through 18 inclusive, additional mechanism is involved, which incorporates a change in the hub 41' operated by the knob 21. On the assumption that such is the outside knob, there is provided in the hub 41 a notch located midway between the stop shoulders 66' and 67' as shown in FIG. 11.

In cooperation with the notch 90 is a locking slide 91. For guiding action of the locking slide 91, there are provided lugs and 96 on opposite edges of the locking slide 91 which slideably engage in the slots 97 and 98 respectively of the case 34 and cover 35 (see FIGS. 17 and 18). This intermemberment prevents moving the slide 91 laterally when in locked engagement with the notch 90 of the hub 41' or when contacted by one or another of the stop shoulders 64 or 65 of the hub 40 or by stop shoulders 66 or 67' of the hub 41', as the case may be.

In either the locked or unlocked condition, the end portion 92 of the locking slide 91 serves as a rotational stop for the hubs 40 or 41' in a like manner as previously described for the end portion 83 of the stop 84 as shown in the forms of the invention of FIGS. 1 through 9 inclusive.

When the end portion 92 of the locking slide91 is in engagement with the notch 90 of the hub 41' the outside knob 21 is locked against rotation and the latch bolt 15 cannot be withdrawn from that side. Withdrawal by operation of the inside knob 19 can, of course, continue as usual.

When it is desirable to lock the outside knob 21, to prevent unauthorized entry, locking action in one form of the invention is created by a shifting of the locking slide 91 from the unlocked condition as shown in FIG. 14 to the locked condition of FIG. 12. In this instance, the axial shifting of the locking slide 91, as viewed moves from right to left until the end portion 92 of the locking slide 91 has entered the notch 90 in the hub 41'. To effect this movement stop works buttons andy101 that project through the face plate 12 are provided. The face plate 12 has recessed areas 99 and 99' for ease in digitally actuating the buttons 100 and 101. The button 100 is affixed to the end of the locking slide 91 and the button 101 is affixed to the end of a secondary slide 110. The secondary slide 110 is guided at the end remote from the button 101 by a slot 111 in the bracket 112. A coupling lever 102 is pivoted about a retaining rivet 113 that is disposed midway between the axis ofthe locking slide 91 and the secondary slide 1 10. The lever 102 is intermembered with the locking slide 91 and the secondary slide 110 by means of respective notches 114 and 115 thereby creating a toggle action between the stop works buttons 100 and 101 such that when the button 100 is pushed inward to effect locking the other button 101 is projected outward to a position where it may in turn be pushed to provide unlocking. To assure that the locking slide 91 is retained in either the locked or unlocked position, a detent action is supplied by the end 104 of a flat spring 103 contacting the lever 102. The spring 103 is held in situ by one of a series of standoffs 116.

The form of invention of FIGS. 1 through 9 inclusive is directed primarily to a disclosure of the retract mechanism and its actuation. The forms of invention of FIGS. 10 through 18 inclusive incorporate additional structures that provide locking means. In one form, by making use of the locking slide 91 and a hub like the hub 41 of FIG. 11 will place the mortise lock in a condition which can be locked on the outside while being free for manipulation on the inside. As is clear from an examination of FIG. 12, even though the hub 41 can be locked by insertion of the end portion 92 of the locking slide 91 in the notch 90, the hub 40 when rotated by manipulation of the inside knob 19, can be moved against either the cam face 68 or the cam face 69 to rotate the retract arm 70 thereby to retract the latch bolt 15. Meanwhile, the door remains locked from the outside.

Even where under circumstances the locking slide 91 is extended into engagement with the notch 90 it is possible to retract the latch bolt by the agency of a conventional outside keyoperated mechanism 106. For adaption of such a key operated lock mechanism 106, there is provided a transverse bore hole 105, shown in FIGS. 12 and 13, for retaining the lock mechanism 106 by means (not shown). The lock mechanism 106 contains a plug 107 that is rotatable by the use of a proper key (not shown). The end of the plug 107 that is within the housing is configured to receive a cam 108. Retraction is accomplished by employment of a first class lever 120, pivotally mounted in the housing 20 by means of the pivot pin 121. The lever 120 is provided with a long arm 122 and a cam face 123 which bears against the retract plate 73. To retract the latch bolt 15, moving in a direction from right to left as seen in FIGS. 12 and 13, a tab 124 on a short arm 125 of the lever 120 is contacted by the cam 108 of the lock mechanism 106 when rotated by a proper key. The resulting movement of the lever 120 causes the cam face 123 to act against the retract plate 73 until such movement is limited by the stop pin 82. Thus equipped as shown and described it remains possible to retract the latch bolt 15 from the outside by use of the key actuated lock mechanism 106 irrespective of the locked or unlocked condition of the outside knob 21.

In the form of the invention of FIGS. 15 and 16, the locking slide 91 is shifted from the unlocked condition as shown in FIG. 15 to the locked condition of FIG. 16 by means of coupling levers that are actuated by the lock mechanism 106. This is accomplished by a proper key rotating the cam 108. When rotated in a counterclockwise direction as viewed in FIG. 15, the cam 108 contacts the corner of a composite lever 131. The composite lever 131 being pivoted about the pin 121 results in a first class lever action against the tab 132 of another first class lever 133 by the intermemberment of the tab 132 within the slot 134 of the composite lever 131. The resulting output at the remote end 135 of the lever 133 is transferred to the locking slide 91 by coupling within the notch 136 whereby the locking slide 91 is axially shifted from right to left as viewed in FIG. 15. In this instance, the locking slide 91 has a modified form of locking button 137 that serves only to guide the end of the locking slide 91 that is remote from the guide slots 97, 98. As will be further noted, the modified locking button 137 is not exposed through the face plate 12 as in this form of the invention actuation of the locking slide 91 is accomplished only by means of the key operated lock mechanism 106. To provide a pivotal mounting for the aforementioned second first class lever 133 a pivot pin 138 in the form of a shoulder rivet is assembled to the case 34.

As was previously pointedout in another form of the invention, a detenting means was required to hold the locking slide 91 in either a locked or unlocked position. As shown in FIGS. 15 and 16, the elements made use of in the prior form have been eliminated in this case, these being the coupling lever 102, its associated secondary slide 1 10 and the detent spring 103. To provide the required detent action, this form of the invention as well makes use of a flat spring 139 that is retained by the standoff 140. The spring 139 has a configured end 141 that cooperates with a portion 142 of the composite lever 131. The detent action thus applied to the composite lever 131 is as well applied to the locking slide 91 by virtue of the interconnection by the lever 133.

As will also be noted in FIG. 15, if the cam 108 is rotated in a clockwise direction, it will by pass the corner 143 of the composite lever 131 until it stops against the tab 124 of the retracting lever 120.

Referring now to FIG. 16 is shown the unlocking action of the mechanism just described whereby the cam 108 when rotated in a clockwise direction will contact the corner 143 of the composite lever 131 causing it as well to rotate in a clockwise direction about the pivot pin 121. As the slot 134 is rotated, its interconnection with the lever 133 will cause the locking slide 91 to be shifted from left to right as viewed into the unlocked condition. As will also be noted in FIG. 16, if the cam 108 is rotated in a counterclockwise direction it will pass the corner 130 of the composite lever 131 until it contacts the tab 124 on the short arm 125 of the retaining lever 120 whereby continued rotation of the cam 108 will effect retraction of the latch bolt 15 as previously described. Thusly, the lock mechanism 106 can serve to lock or unlock the hub 41' or provide latch bolt retraction alone without causing the locking action to be disturbed.

In a modification of the form of the invention just described, two lock mechanisms 106 may be made use of whereby one is mounted to each face of the door 11. In this modified instance, the lock mechanism 106 that is actuable from the inside of the door 11 would operate the loeking and unlocking functions as described. The other lock mechanism 106 operable from the outside of the door 11 would be provided with a modified form of the cam 108 whereby it would not actuate the composite lever 131 and only cooperate with the retracting lever 120 to provide latch bolt retraction when the outside knob 21 has been placed in a locked condition.

The bearing 71 of the retract arm 70, previously made reference to is shown in cross section detail in FIG. revealing its attachment to the retract arm 70 by staking its lower end 146. The bearing 71 pivots about a standoff 147. The series of standoffs 116, 140 and 147, in addition to their previously described usage, serve to retain the cover 35 in a properly clear position on the case 34 by means of a series of screws 148 that threadably engage the series of standoffs 116, 140 and 147. The standoffs 116, 140 and 147 are retained in the case 34 by staking such as the staking 149 for the standoff 147 as shown in FIG. 5. The bearing 71 also serves as a hub for the torsion spring 74, one end of which contacts the rear wall of the case 34 and the other end which enters a hole 150 in the turned back portion 151 of the retract arm 70. This turned back portion 151 also serves as a support brace for the cam surfaces 68, 69 and has on its upper edge two arcuate projections 152, 153 that provide a minimum contact area against the cover 35 to reduce sliding friction when the retract arm 70 is pivoted.

Throughout the cycle of operation of the several forms of the invention no portion of the mechanism interferes or passes through the openings 36, 37 in the case 34 or the matching openings 38, 39 in the cover 35 thereby allowing the posts 28, 29 and the sleeves 30, 31 to pass freely through the casing 20.

Having described the invention, what is claimed as new in support of Letters Patent is:

1. In a mortise type lock having a case with a reciproeating latch bolt member mounted therein and a rotatably mounted hand hold assembly having a spindle non-rotatably attached thereto,

the comination of a latch bolt retracting mechanism comprising a rollback element non-rotatably mounted on the spindle,

said roll back element having two arcuate rollback surfaces facing each other and extending in a generally radially outward direction relative to the center of rotation of the spindle, a retract arm pivotally mounted in the case and in retracting engagement with said latch bolt member,

cam faces on said retract arm angularly disposed relative to each other and at different distances from said pivotal mounting for engagement with the respective rollback surfaces,

one of said cam faces being at one angle relative to a radial line from the pivotal axis to the point of intersection of said cam faces and the other cam face being at another angle relative to said radial line, whereby torque forces and rotational input of said hand hold in opposite directions of rotation of the spindle are about equal.

2. A mortise type lock as in claim 1 wherein said cam faces are offset relative to a radial line from the axis of pivotal mounting and the point of engagement of said retract arm with the latch bolt member.

3. A mortise type lock as in claim 1 wherein there is a pair of sleeve-like connecting means extending from the hand hold assembly through the case, said connecting means being spaced diametrically on opposite sides of said spindle and at locations clear of said rollback element.

4. A mortise type lock as in claim 1 wherein there are two hand holds on respective opposite sides of the case and a rollback non-rotatably attached to each hand hold, both of said rollbacks being in engagement with the same retract arm.

5. A mortise type lock as in claim 4 wherein one of said rollbacks has a radially inwardly extending locking notch and a reciprocatable locking slide adapted to engage said locking notch in locking position.

6. A mortise type lock as in claim 5 wherein there is a stop works button on said locking slide extending outward relative to an end edge of said case.

7. A mortise type lock as in claim 5 wherein there are two interconnected stop works buttons, one of said buttons being on the locking slide and the other comprising a slide with button attached, said locking slide being adapted to engage said locking notch and the other of said buttons being an unlocking button.

8. A mortise type lock as in claim 5 wherein there is a lever pivotally mounted in the case, one end of said lever being in engagement with the locking slide and a key actuable lever pivotally mounted on the case and in engagement with another end of said first lever whereby to operate said locking slide by auxiliary action.

9. A mortise type lock as in claim 1 wherein there is a second retract arm pivotally mounted on said case, one end of said second retract arm being in engagement with the latch bolt and another end of said second retract arm having a key actuatable tab operable independently of said first retract arm to withdraw said latch bolt.

10. A mortise type lock as in claim 3 wherein the pivotal mounting of said retract arm is spaced laterally from a diametrical line interconnecting said connecting means and at a distance from the axis of rotation of said spindle greater than the distance from said axis of rotation of the spindle and either of said connecting means.

11. A mortise type lock as in claim 1 wherein there is a pair of shoulders on the side of said rollback opposite from said rollback surfaces and a stop on the case adapted to engage said shoulders in the alternative whereby to limit rotation of the rollback.

12. A mortise type lock as in claim 4 wherein there is a pair of shoulders in the side of each rollback opposite from the rollback surfaces and a stop in the case adapted to engage said shoulders in the alternative whereby to limit rotation of the respective rollback.

13. A mortise type lock as in claim 8 wherein said key actuable lever is detented in two selected positions, said detent means being adjacent to and acting directly upon said key actuable lever, said two positions being locked and unlocked conditions.

14. A mortise type lock as in claim 5 wherein said rollbacks each contain a pair of shoulders in the side of each rollback opposite from the rollback surfaces and said locking slide acts as a stop to engage said shoulders in the alternative whereby to limit rotation of respective said rollbacks regardless of locked or unlocked position of said locking slide.

15. A mortise type lock as in claim 4 wherein both said rollbacks have radially inward extending locking notches and a locking element adapted to engage both of said locking notches.

16. A mortise type lock as in claim 5 wherein said locking slide contains a pair of opposite projecting lugs,

said lugs engageable within sloted openings in respective opposite walls of said case.

17. A mortise type lock as in claim 1 wherein said retract arm contains; a bearing portion coaxial with said pivotal mounting, an overlying portion supporting said 5 angular cam surfaces, a torsion spring acting between said case and an aperature in said overlying portion, the 

1. In a mortise type lock having a case with a reciprocating latch bolt member mounted therein and a rotatably mounted hand hold assembly having a spindle non-rotatably attached thereto, the comination of a latch bolt retracting mechanism comprising a rollbacK element non-rotatably mounted on the spindle, said roll back element having two arcuate rollback surfaces facing each other and extending in a generally radially outward direction relative to the center of rotation of the spindle, a retract arm pivotally mounted in the case and in retracting engagement with said latch bolt member, cam faces on said retract arm angularly disposed relative to each other and at different distances from said pivotal mounting for engagement with the respective rollback surfaces, one of said cam faces being at one angle relative to a radial line from the pivotal axis to the point of intersection of said cam faces and the other cam face being at another angle relative to said radial line, whereby torque forces and rotational input of said hand hold in opposite directions of rotation of the spindle are about equal.
 2. A mortise type lock as in claim 1 wherein said cam faces are offset relative to a radial line from the axis of pivotal mounting and the point of engagement of said retract arm with the latch bolt member.
 3. A mortise type lock as in claim 1 wherein there is a pair of sleeve-like connecting means extending from the hand hold assembly through the case, said connecting means being spaced diametrically on opposite sides of said spindle and at locations clear of said rollback element.
 4. A mortise type lock as in claim 1 wherein there are two hand holds on respective opposite sides of the case and a rollback non-rotatably attached to each hand hold, both of said rollbacks being in engagement with the same retract arm.
 5. A mortise type lock as in claim 4 wherein one of said rollbacks has a radially inwardly extending locking notch and a reciprocatable locking slide adapted to engage said locking notch in locking position.
 6. A mortise type lock as in claim 5 wherein there is a stop works button on said locking slide extending outward relative to an end edge of said case.
 7. A mortise type lock as in claim 5 wherein there are two interconnected stop works buttons, one of said buttons being on the locking slide and the other comprising a slide with button attached, said locking slide being adapted to engage said locking notch and the other of said buttons being an unlocking button.
 8. A mortise type lock as in claim 5 wherein there is a lever pivotally mounted in the case, one end of said lever being in engagement with the locking slide and a key actuable lever pivotally mounted on the case and in engagement with another end of said first lever whereby to operate said locking slide by auxiliary action.
 9. A mortise type lock as in claim 1 wherein there is a second retract arm pivotally mounted on said case, one end of said second retract arm being in engagement with the latch bolt and another end of said second retract arm having a key actuatable tab operable independently of said first retract arm to withdraw said latch bolt.
 10. A mortise type lock as in claim 3 wherein the pivotal mounting of said retract arm is spaced laterally from a diametrical line interconnecting said connecting means and at a distance from the axis of rotation of said spindle greater than the distance from said axis of rotation of the spindle and either of said connecting means.
 11. A mortise type lock as in claim 1 wherein there is a pair of shoulders on the side of said rollback opposite from said rollback surfaces and a stop on the case adapted to engage said shoulders in the alternative whereby to limit rotation of the rollback.
 12. A mortise type lock as in claim 4 wherein there is a pair of shoulders in the side of each rollback opposite from the rollback surfaces and a stop in the case adapted to engage said shoulders in the alternative whereby to limit rotation of the respective rollback.
 13. A mortise type lock as in claim 8 wherein said key actuable lever is detented in two selected positions, said detent means being adjacent to and acting directly upon said key actuable lever, said two positions beiNg locked and unlocked conditions.
 14. A mortise type lock as in claim 5 wherein said rollbacks each contain a pair of shoulders in the side of each rollback opposite from the rollback surfaces and said locking slide acts as a stop to engage said shoulders in the alternative whereby to limit rotation of respective said rollbacks regardless of locked or unlocked position of said locking slide.
 15. A mortise type lock as in claim 4 wherein both said rollbacks have radially inward extending locking notches and a locking element adapted to engage both of said locking notches.
 16. A mortise type lock as in claim 5 wherein said locking slide contains a pair of opposite projecting lugs, said lugs engageable within sloted openings in respective opposite walls of said case.
 17. A mortise type lock as in claim 1 wherein said retract arm contains; a bearing portion coaxial with said pivotal mounting, an overlying portion supporting said angular cam surfaces, a torsion spring acting between said case and an aperature in said overlying portion, the helical portion of said torsion spring coaxially positioned about said bearing portion.
 18. A mortise type lock as in claim 4 wherein both said rollbacks are supported in said case by low friction bearing inserts. 